An allergy is a reaction of your
immune system to something that does not
bother most other people. People who
have allergies often are sensitive to
more than one thing. Substances that
often cause reactions are

How do you get allergies? Scientists
think both genes and the environment
have something to do with it. Normally,
your immune system fights germs. It is
your body's defense system. In most
allergic reactions, however, it is
responding to a false alarm.

Allergies can cause a runny nose,
sneezing, itching,
rashes, swelling or
asthma. Symptoms vary. Although
allergies can make you feel bad, they
usually won't kill you. However, a
severe reaction called anaphylaxis is
life-threatening.